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406 cooling fan problem

Someone (who shall be nameless) impaled our 406 on the towbar of a vehicle which stopped unexpectedly. The damage seemed superficial but turned out to include a busted fan blade (and goodness knows what else). My question is: can the damaged fan motor be safely disabled (until the repairs can be carried out) by disconnecting the motor on that fan or will this cause problems (through confusing the control system?)

I have in mind the following post by Bob minchin some years ago (and I have confirmed that my 406 uses the Bitron controller he describes:

If the 406 is anything like the 405 in this respect, the control of the cooling fans is managed by a module known as a Bitron which takes inputs from the Aircon controller and a sensor built into the radiator and then decides whether to switch the fans on either in series or parallel by means of three relays mounted behind the front grill alongside the fans. With a cold engine and air off, the fans should not turn at all. switch on the aircon and fans should run in series ie low speed. If the engine gets hot when aircon is on or off, the fans run in parallel ie fast. If one fan runs and the other does not when in series, it just means one need freeing up /oiling. If one does not run when they are meant to be fast, suspect a relay or motor.

Reply to
Ken
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Digging in the Haynes manual reveals that Fuse F6, in Battery fusebox two seems to control the RH fan, while F7 is for the other. So an alternative way of disabling the RH fan would be to remove F7. But I find the wiring diagram very confusing as to what happens to the fuses when the fans are in series or parallel.

Reply to
Ken

Ken The fan motors are self connecting when the 3 fixing bolts are tightened. You would therefore have to remove the motor to carry out the temporary fix you are proposing. This is not an easy job as you have to move the radiator Air con rad and intercooler out of the way to get at the fan fixings. As suggested by another reader there are 2 X 40 amp fuses in the engine compartment fusebox. One is used to power both fans at slow speed. Both are required feeding each fan separately when on high speed. You could try removing each fuse in turn with the brown thermostat wire removed to make sure you have the correct fan disabled. Warning you will nolonger have slow speed cooling available and fast speed will come in at

118degrees.

An explanati> > Someone (who shall be nameless) impaled our 406 on the towbar of a

Reply to
Michael Roche

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Thanks Michael.

Reply to
Ken

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I'm not quite sure how these fuses will be wired in on the 406 but I suspect it will be simply one for each fan. Hence when operating in series both fuses will needed, pulling one will likely stop both fans. This need not be a disaster. The cooling system will expect the fans to be on slowly to start with but if they don't run, the radiator will warm up quicker and the Bitron will put the fans in parallel, but in your case only one will work. There will be less cooling power but in the UK and this time of year you should not need too much cooling. I suggest you try and avoid long traffic queues and don't use the aircon.

HTH

Bob

Reply to
Bob Minchin

Thanks Bob, and for your other posts - some of which I have printed out and keep with my Haynes. I am in Oz - Canberra - outside temperature now - around midday - about 10c.

Reply to
Ken

Ken The 3 relays perform the following function :-

1) switches live to either both fans in series or left fan only (this is cross connected to the changeover relay) 2) change over relay either used to provide series connection to right fan (slow speed) or earth connection for left fan (high speed) 3) switches live feed to right fan only used for high speed.

Therefore if the damaged fan blade is on the right fan, pulling the fuse for the left fan/ slow speed working will provide a temporary fix.

It should be noted that these relays energise when provided with an earth from the Bitrol unit. Mike

Reply to
Michael Roche

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